Investigation For Effects Of Static Eccentricity On Dynamic Characteristics Of Squeeze Film Damper

In virtue of obvious damping effect and simple structure,squeeze film damper(SFD)has been one of the widely used means in aero-engine.Therefore mastering the dynamic characteristics of squeeze film damper,has become an important and effective way to improve the aero-engine vibration problem,In the current study,Most of theory research focus on how to accurately solution of oil film pressure while less in the static eccentricity,which caused by weight of the rotor,assembly error and so on.The influence of this static eccentricity on the rotor system is the focus of this paper,aiming at the static eccentricity.The main contents and innovations of this paper are listed as follows:(1)The dynamic models of SFD with static eccentricity is established,which is based on the general Reynolds equation,and then obtain solution of the equation by using difference method.Then correctness of the model is validated by comparing with the results of Fluent;(2)Studied the sealing gap of squeeze film damper,impact state and working environment on the characteristics of oil film force by Fluent and difference method,Research shows that when the sealing gap is small,the simulation pressure distribution will be larger deviation of the true activity if the boundary pressure is ignored;increase of working temperature will rapidly deteriorate the performance of damper.The static eccentricity will make the stiffness and damping of the oil film alternating with time,the increase of the static eccentricity ratio will increase the stiffness and damping of the oil film in the same dynamic eccentricity ratio;(3)A double disk single rotor model with 1-0-1 support is established by transfer matrix method.Utilizing Newmark-beta and Newton-Raphson method,the influence of static eccentricity to dynamic characteristics was analyzed,Research results show that the static eccentricity will cause the critical speed of the rotor increases,the sudden unbalance transient response amplitude increases,the rotor is no longer suitable for the assumption of isotropy;The squirrel cage force increases rapidly due to static eccentricity,deteriorates the working conditions of foundations.Therefore,in order to ensure that the rotor dynamic characteristics are consistent with the design,the rotor static eccentricity ratio should be controlled within 0.2;(4)Using transfer matrix method to establish double rotor model with intermediate bearing,After that,preliminary analysis the relationship between static eccentricity and dynamic characteristics of double rotors.The results show that when the inner rotor with static eccentricity,the dynamic equilibrium position of outer rotor deviates from the engine axis,due to the influence of the oil film force and the intermediate bearing,which will increase the risk of contact rubbing fault.